A 3.75-gram sample of limestone, CaCO3, contains 1.50 g of calcium and 0.450 g of carbon. What is the percent oxygen in limestone?

A substance X2Z has the composition (by mass) of 40.0% X and 60.0% Z. What is the composition (by mass) of the compound XZ2?

How many H atoms are present in 7.52 g of propane, C3H8?

The acid–base reaction between phosphoric acid, H3PO4, and calcium hydroxide, Ca(OH)2, yields water and calcium phosphate. For each mole of calcium phosphate produced by this reaction, how many moles of water are produced?

Quartz, SiO2, contains 46.7% silicon. What mass of silicon is present in 370 g of quartz?

Vitamin B12, cyanocobalamin, is essential for human nutrition. Its molecular formula is C63H88CON14014P. A lack of this vitamin in the diet can lead to anemia. Cyanocobalamin is the form of the vitamin found in vitamin supplements. What is the mass (in grams) of one molecule of cyanocobalamin?

A 3.000 g sample of a gaseous compound was found to contain 2.560 g of carbon and 0.440 g of hydrogen. A) What is the simplest formula of the compound (Write C first and then H)? You won't be able to make the numbers a subscript. For instance, for MgCl2 enter MgCl2. B) The molar mass of the compound was found to be 42.08 g/mol. What is the molecular formula of the compound? You won't be able to make the numbers a subscript. For instance, for MgCl2 enter MgCl2.

Lead is found in Earth’s crust as several different lead ores. Suppose a certain rock is 38.0% PbS (galena), 25.0% PbCO3 (cerussite), and 17.4% PbSO4 (anglesite). The remainder of the rock is composed of substances containing no lead. How much of this rock (in kg) must be processed to obtain 5.0 metric tons of lead? (A metric ton is 1000 kg.)

7. What is the mass percent of silicon dioxide (SiO2) if you are able to separate 2.202 g out of a 6.626 g unknown sample?

I have a question that states: “What is the mass percent of silicon dioxide (SiO2) if you are able to separate 2.202g out of a 6.626g unknown sample? To solve this problem, wouldn’t I divide 6.626g by 2.202g and then add 100 to that product?